Yamaha DT125R '01 - Running Project
-
Prototype V4, 3D printed in a TPU at 80A Shore Hardness like the original. This is chemical and UV resistant filament and it's rather tough!
This is the final design for use with a pressure mold.
Concessions need to be made for 3D printing rubber unfortunately, so now I'm using M5 Socket cap bolts and the original flange that's molded in the Airbox as a sealing face, it actually works out to be the most effective alternative. Much like a YZ Airbox will use the same design.
The Airbox is so important when jetting a 2stroke road bike, we need to control the flow of air and have a place to store some also! Induction theory carries on. The area inside is free of interruption and the boot helps to increase the velocity upon entering the carb. I'm hoping to gain more torque down low by using that stock Airbox volume.
The design now minimises any angles greater than 55deg, this means material does not have to be supported as we print. As you can see, this is the optimal version as the rest of the print can completed cleanly as a vertical slice.
Job done,
So much more flexibility with jetting. Measure 69 times, draw it once.
Mikuni TM34ss finally finished.
-
Global pandemic huh? returns to shed
Not been doing alot, just wanted to share some bits.
After 4 years, finally built a proper DTX Brembo Caliper conversion. Threw some Titanium bolts on for some weight saving, and bling.
Custom Bracket and Spacers made, was fun on the old Myford Lathe. Got to force yourself to work in Imperial though...,
Plenty of braking power with Ceramic Pads on a 298mm Disc. To manage the DTR Fork, I've rebuilt them with 15W Oil and 35mm Spring Top Hat spacers, this effectively shortens the spring travel and keeps the spring in its stiffest part of the stroke. It works well enough for me at 70kg.
Could be better, but you can pedal this thing hard into mid corner so it feels pretty sorted for road use.
I've got a USD setup in bits currently, got a set off NOS 1996 YZ250 Forks, if anything, they just look sick.
I will do a Build thread on installing USD forks for the DTR, as I think many people want to do it but are not sure about the parts needed to do so.
Re-mounted my Ignitech CDI with rubber mounts and polished up my bracket, sadly it seems the company has disappeared. I've never had a problem with my unit and this Programmable CDI is the best thing I ever bought for this project.
The spark on this thing is ridiculously good.
I couldn't be bothered to fix my ported 3MB 'P' 134cc Cylinder so i went back to my old 14,000 Mile standard bore 3MB
Cylinder with a TDR unrestricted Head, and it has been so much fun to ride. Just a torqueey reliable DT engine like I remember it when I was 17.QUICK ENOUGH LOL
Been running different carbs for a few years now, and I have to say you couldnt do much better than well Setup Mikuni TM28ss and the 30ss from a WR200 is brilliant for the 125R.., depending on how good you can setup the floats and mixture.
This is the problem with any carburettor using the standard Inlet,
MIKUNI TM28SS - TM30SS - TM32 - TM34SS - KEIHIN PWK36
My favourite so far has been setting up a Mikuni TM34SS from a Aprilia RS250 and Later model RGV250s, (Same engine)
Mainly, the Venturi is angled so the Fuel Bowl remains level. But it has a really effective power jet and has been easy to setup, it works really well with just 125cc, this engine barks and pulls great at Mid-Range too. For me, I pretty happy keeping this engine under 140cc. It's plenty fun.
I'm using a Modified WR200 Inlet with Boyseen DT200R Reeds. Runs good.
I have a 3D printed Airbox to Carb boot I designed, so it's water tight and easier to jet than a Pod Filter.
Currently waiting to print a new filament that has the right Shore Hardness to produce a rubber part like the original. You need a good amount of flex to seat the airbox and carb together.
This has all been paired with old Nikkon Race exhaust, Handmade, Gas welded steel. There is pretty much no info on these.
I bought this from a guy who used it a couple of times and then stored it for 10 years, as far as I know this is the only DT125R Nikkon pipe left in existence. Which is a shame, because this pipe is so much better than the DEP on the road.
I'm going to copy this pipe into Stainless steel and just keep it the way it is because it suites my application so well. Very large expansion pipe aswell, the design is unique.
Will go further into the restoration of it as it's currently covered in BBQ Black paint.
Long term project aye, I've already had my fun.
@Darty tm34ss is the perfect upgrade due the the shape and angle, keeps the float bowl level .
I think there's a tm36ss also -
Exhaust Porn
This was the last one ever left, I finally bit the bullet and purchased a Stainless exhaust for the DT.
This came all the way from bloody Portugal like this
Great job lads.
Ballin' - This is the 'YAMAHA DT125 Special Exhaust' in STAINLESS DTX DTR-E with end can from Romeu125 an eBay seller.
Custom design by the gang over there and beautifully hand made.Really quite impressed, only ever 4 sold on eBay.
Looks great, low slung - Interesting design. I've got to say, did not fit that well with the tail pipe supplied. It was so awkward in fact I decided to fit my WR200 FMF tail pipe DIY instead.
Looks cool, but too raspy for my taste.
Picked up maybe the last NOS WR200 Mikuni Idle screw ever? This stuff is all getting expensive and stupidly hard to come by these days...Airbox
Next up, finishing up the Airbox. Drilled and bolted up with M5 bolts and importantly using Nylocs. Can't have the ingestion of M5 bolts into the crankcase.
Got it bang on with a perfect seal, sadly it's no going back with the install but that's the best that can be achieved SLA 3D printing.
WR200 SideStand - 1991-1993
The early versions of the WR200 came with a long enduro style kickstand. Almost impossible to find nowadays and I'm kicking myself for not getting one NOS from Fowlers back in the day, but I was a student at the time.
Due to the design you need to notch the DTR frame, so 'sayonara' fresh powdercoat here and sent it with the Grinder. It looks like I've cut to far there, but it's just swarf.
Again, NO GOING BACK.
The WR200 sidestand looks mint, tucks up nicely and props the bike up much further if you run an increased ride height over standard on the DTR.
(New longer spring needed)
FINAL FORM
I'm running DT230 Lanza Frame Guards, Left handside here is a ZETA part. Otherside is an OEM Lanza Part which only fits right handside for the DTR and require spacers and machining to fit the DTR. But worth it.
HOT BOI
Such an odd Croissant that pipe....,
I think that's it for the DTR, It's a beast, sounds great and is still alot of fun 7 years on. But it's had it’s day.
Is it better? All I'm certain is that it's mine.
. -
I just ground down the ends of them as they wouldn't sit flush. It's a very minor mod I didn't think twice about it.
-
Yeah it was simple. I tried looking I could find exactly what I bought. I must have done it after I "finished" my bike and thus didn't document it. But yeah was a really easy mod and now I have Phat footrests.
-
@Calum Really nice! My only problem is the budget, those things are like a 100€
Maybe I should get some Chinesium ones 
-
Global pandemic huh? returns to shed
Not been doing alot, just wanted to share some bits.
After 4 years, finally built a proper DTX Brembo Caliper conversion. Threw some Titanium bolts on for some weight saving, and bling.
Custom Bracket and Spacers made, was fun on the old Myford Lathe. Got to force yourself to work in Imperial though...,
Plenty of braking power with Ceramic Pads on a 298mm Disc. To manage the DTR Fork, I've rebuilt them with 15W Oil and 35mm Spring Top Hat spacers, this effectively shortens the spring travel and keeps the spring in its stiffest part of the stroke. It works well enough for me at 70kg.
Could be better, but you can pedal this thing hard into mid corner so it feels pretty sorted for road use.
I've got a USD setup in bits currently, got a set off NOS 1996 YZ250 Forks, if anything, they just look sick.
I will do a Build thread on installing USD forks for the DTR, as I think many people want to do it but are not sure about the parts needed to do so.
Re-mounted my Ignitech CDI with rubber mounts and polished up my bracket, sadly it seems the company has disappeared. I've never had a problem with my unit and this Programmable CDI is the best thing I ever bought for this project.
The spark on this thing is ridiculously good.
I couldn't be bothered to fix my ported 3MB 'P' 134cc Cylinder so i went back to my old 14,000 Mile standard bore 3MB
Cylinder with a TDR unrestricted Head, and it has been so much fun to ride. Just a torqueey reliable DT engine like I remember it when I was 17.QUICK ENOUGH LOL
Been running different carbs for a few years now, and I have to say you couldnt do much better than well Setup Mikuni TM28ss and the 30ss from a WR200 is brilliant for the 125R.., depending on how good you can setup the floats and mixture.
This is the problem with any carburettor using the standard Inlet,
MIKUNI TM28SS - TM30SS - TM32 - TM34SS - KEIHIN PWK36
My favourite so far has been setting up a Mikuni TM34SS from a Aprilia RS250 and Later model RGV250s, (Same engine)
Mainly, the Venturi is angled so the Fuel Bowl remains level. But it has a really effective power jet and has been easy to setup, it works really well with just 125cc, this engine barks and pulls great at Mid-Range too. For me, I pretty happy keeping this engine under 140cc. It's plenty fun.
I'm using a Modified WR200 Inlet with Boyseen DT200R Reeds. Runs good.
I have a 3D printed Airbox to Carb boot I designed, so it's water tight and easier to jet than a Pod Filter.
Currently waiting to print a new filament that has the right Shore Hardness to produce a rubber part like the original. You need a good amount of flex to seat the airbox and carb together.
This has all been paired with old Nikkon Race exhaust, Handmade, Gas welded steel. There is pretty much no info on these.
I bought this from a guy who used it a couple of times and then stored it for 10 years, as far as I know this is the only DT125R Nikkon pipe left in existence. Which is a shame, because this pipe is so much better than the DEP on the road.
I'm going to copy this pipe into Stainless steel and just keep it the way it is because it suites my application so well. Very large expansion pipe aswell, the design is unique.
Will go further into the restoration of it as it's currently covered in BBQ Black paint.
Long term project aye, I've already had my fun.
-
@Darty what ignitec cdi did you go for?? Ive sent an email and they have recommended the DCCDIP1 race
@finchfocker I myself just bought the DCCDIP1 race. Seems like a great unit, just programmed myself a ignition map to start off with, hopefully I'll get a chance to plug her in soon!
Perfect then!
